I've been a 2016 Airstream Interstate with VB air suspension owner since October 2015. One of the first things I looked into was the addition of more solar panels. Ours came with the single 100 watt panel.
I went on Amazon and ordered the Go Power flexible panels, exactly the same that the airstream came with. They were also half price of what the dealer was charging.
I know that some people criticize these panels, but I liked the fact that they were flexible and seemed very durable, and that they could be mounted pretty much flat on the roof without adding any more aerodynamic drag, and that they could be attached with industrial double stick tape.
Amazon had single expansion panels for around $511 each. Although they also had a deal with a 200watt kit hat included a charge controller. This kit was about the same cost for just the two panels. So I bought the kit just to have a spare charge controller and extra cables. I also bought a cable splitter with the correct connectors.
It was a pretty simple installation, I didn't have to drill holes, and now my vehicle will stay well charged even when leaving it with the refrigerator on and the vent fan blowing.
The 3M VHB mounting tape (industrial double stick tape) was plenty strong to hold the panels in place. Took them on a 3500 mile road trip at speeds up to 82 mph (speed limiter kicks in at 82) with no evidence of the panels coming loose.
One of the issues that drove me to put on the extra panels was because when the engine was running, it was not charging the house batteries. It turned out to be a mis-wired battery isolation manager. Even the dealer took a while to figure this out even though I told them to check for certain known problem areas such as the BIM. Now that the coach charges the batteries too (when driving, and I drive the Interstate almost every day) I never see the battery capacity drop below 70%. I always leave the refrigerator on, and at worst overnight maybe the battery drops to 80%.
I wish I could change the wires going into the Interstate from the solar panels to a higher gauge, but I don't think this can be done easily. (??)
The power blinds on the 2016 has its pluses and minuses. It's cool to be able to grab the remote and have all the blinds or screens be at your fingertips. However, they really rattle while driving down the less than smooth roads, and that's even with the air suspension option. The other issue is that if they are out of adjustment, (hanging too low, etc) then you have to take to the dealer to adjust. I'm still asking around to find out if anyone has done their own adjustment.
What I'm adding now are some small rolls of bubble wrap wedged between the blind and screen in order to hold them still while driving. But they fall out as soon as you drop the blinds.
Next thing to add would be an in-motion satellite dome. Looks like people put those up at the front above the driver, probably to use the hole where the satellite radio antenna goes in.